1. Technical Field
The present invention relates to battery packs and components thereof.
2. Description of the Related Art
Conventional lithium polymer soft pack batteries use prismatic or cylindrical cans or rectangular boxes as a package for the battery cells as seen by reference to U.S. Pat. No. 5,639,571 issued to Waters, et al. However, these packages are heavy and expensive, which are disadvantages. In addition, conventional lithium polymer soft pack batteries further use nickel, copper or aluminum terminals to carry current through the package seal to the outside for connection to an overall package connector. These terminals are arranged to exit the same side of the package and are adjacent to each other. The foregoing xe2x80x9csame-sidexe2x80x9d arrangement, however, has shortcomings.
One of the problems involves leaking of the electrolyte solution at a seal point of the terminal to the package. Another problem relates to the orientation of the terminals on the same side. Specifically, the terminals are arranged to exit on the same side of the package and are adjacent to each other, making it difficult to electrically connect the packages in a compact configuration.
There is therefore a need for an improved battery pack that minimizes or eliminates one or more of the problems set forth above.
It is an object of the present invention to provide a solution to one or more of the above mentioned problems. In one aspect of the present invention, a battery pack is provided that includes a flexible connective circuit containing conductive traces and flaps extending from windows cut from a substrate thereof. One advantage is that these traces and flaps allow for power and control electrical connections between and among a plurality of battery modules in a reduced weight arrangement. Additionally, the flexible circuit allows battery modules to be connected in series (for greater output voltage), or in parallel (for greater ampacity).
According to the first aspect, a battery pack is provided that includes a plurality of battery modules each having at least a positive terminal and a negative terminal associated therewith, and a flexible circuit configured to connect the plurality of positive and negative terminals to an overall output of the battery pack. In a preferred embodiment, each module includes a plurality of individual battery units (sometimes referred to as a xe2x80x9csoft packxe2x80x9d), each battery unit including a plurality of bicells.
In a second aspect of the present invention, a pair of terminals associated with a battery unit are located on opposing sides of the battery unit, allowing the battery unit to be rotated one relative to an adjacent one and placed directly thereon. The process can be repeated to form battery modules. This arrangement allows a compact stacking of battery units.
According to the second aspect, a battery unit is provided that includes a (i) plurality of bicells, each bicell containing anodic exposed grids and cathodic exposed grids, the cathodic exposed grids being located across the bicell on the other side of the anodic exposed grids, (ii) a positive terminal, (iii) a negative terminal that is located across the bicell on the other side of the positive terminal, and (iv) a packaging envelope. In a preferred embodiment, a plurality of battery units are each stacked upon the previous battery unit, having been rotated 180 degrees around an axis.
In a third aspect of the present invention, a terminal for a battery unit includes a region that contains through apertures along a length dimension of the terminal. The apertures allow an adhesive or the like to flow through the apertures from a first side to a second side of the terminal to thereby form an improved seal. Additionally, in a preferred embodiment, a convoluted arrangement of apertures is used which presents a corresponding convoluted edge path. Such a path would require an electrolyte solution to travel a further distance before it could leak through the individual battery cell package, thereby reducing or eliminating the occurrence of leaking.
According to the third aspect, a terminal for a battery unit is provided that includes an electrically conductive body portion having a main axis associated therewith, including a first region configured to be adhered to and in electrical contact with exposed bicell grids, a second region extending along the axis and having a plurality of apertures therethrough, a third region encapsulated by an electrical insulating material, and a fourth region configured for electrical connection to a conductor.
Other features, objects, and advantages will become apparent to one of ordinary skill from the following detailed description and accompanying drawing illustrating the invention by way of example but not by way of limitation.